The electromechanical substrate for response to cardiac resynchronization therapy in patients with right bundle branch block.

BACKGROUND: Some patients with RBBB may respond to cardiac resynchronization therapy (CRT). However, little is known regarding the electromechanical substrate for CRT and whether this is the optimal pacing strategy. METHODS: This was a pilot prospective double crossover randomized controlled clinical study comparing ventricular back up pacing (VVI-40), RV fusion pacing (DDD-40, RV only), and biventricular (BIV) pacing (DDD-40 BIV) in nine patients with RBBB and depressed EF. The study compared the frequency of dyssynchrony on baseline echocardiogram in patients with RBBB (n = 4), RBBB + anterior MI (RBBB with left axis deviation + left ventricular (LV) anterior wall thinning, n = 3), and RBBB + LAFB (RBBB with left axis deviation without LV anterior wall thinning n = 2). Echocardiographic assessment of LV dyssynchrony, LV size, and LV function was repeated after 6 months in each pacing mode. RESULTS: Patients with RBBB + LAFB demonstrated baseline echocardiographic dyssynchrony between the LV anterior and inferior wall. Both DDD-40 RV-only pacing and DDD-40 BIV pacing resulted in improved LV function and clinical status compared to VVI-40 back up pacing. Patients with RBBB alone and RBBB with anterior MI had no baseline dyssynchrony and CRT using either RV only or BIV pacing resulted in LV dilation, worsened left ventricular ejection fraction and worsened clinical status compared to VVI-40 back up pacing. CONCLUSION: Patients with RBBB, left axis deviation, and no prior anterior MI may have LV dyssynchrony between the anterior and inferior walls that is correctable with CRT.

Algorithm for the automatic computation of the modified Anderson-Wilkins acuteness score of ischemia from the pre-hospital ECG in ST-segment elevation myocardial infarction.

BACKGROUND: The acuteness score (based on the modified Anderson-Wilkins score) estimates the acuteness of ischemia based on ST-segment, Q-wave and T-wave measurements obtained from the electrocardiogram (ECG) in patients with ST Elevation Myocardial Infarction (STEMI). The score (range 1 (least acute) to 4 (most acute)) identifies patients with substantial myocardial salvage potential regardless of patient reported symptom duration. However, due to the complexity of the score, it is not used in clinical practice. Therefore, we aimed to develop a reliable algorithm that automatically computes the acuteness score. METHODS: We scored 50 pre-hospital ECGs from STEMI patients, manually and by the automated algorithm. We assessed the reliability test between the manual and automated algorithm by interclass correlation coefficient (ICC) and Bland-Altman plot. RESULTS: The ICC was 0.84 (95% CI 0.72-0.91), P<0.0001. The mean difference between manual and automated acuteness score was 0.17±0.66. In only two cases, there was a major disagreement between the two scores. There was an excellent agreement between the scores for the remaining 48 ECGs, all within the upper (1.46) and lower (-1.12) limits of agreement. CONCLUSION: In conclusion, we have developed an automated algorithm for measurement of the modified Anderson-Wilkins ECG acuteness score from the pre-hospital ECG in STEMI patients. This automated algorithm is highly reliable, can be applied in daily practice for research purposes and may be implemented in commercial automated ECG analysis programs to achieve practical use for decision support in the acute phase of STEMI.

Prehospital electrocardiographic acuteness score of ischemia is inversely associated with neurohormonal activation in STEMI patients with severe ischemia.

BACKGROUND: Elevated levels of N-terminal pro brain natriuretic peptide (NT-proBNP) are associated with adverse cardiovascular outcome after ST elevation myocardial infarction (STEMI). We hypothesized that decreasing acuteness-score (based on the electrocardiographic score by Anderson-Wilkins acuteness score of myocardial ischemia) is associated with increasing NT-proBNP levels and the impact of decreasing acuteness-score on NT-proBNP levels is substantial in STEMI patients with severe ischemia. METHODS: In 186 STEMI patients treated with primary percutaneous coronary intervention (pPCI), the severity of ischemia (according to Sclarovsky-Birnbaum severity grades of ischemia) and the acuteness-score were obtained from prehospital ECG. Patients were classified according to the presence of severe ischemia or non-severe ischemia and acute ischemia or non-acute ischemia. Plasma NT-proBNP (pmol/L) was obtained after pPCI within 24hours of admission and was correlated with the acuteness-score. RESULTS: NT-proBNP levels were median (25th-75th interquartile) 112 (51-219) pmol/L in patients with non-severe ischemia (71.5%) and 145 (79-339) in patients with severe ischemia (28.5%) (p=0.074). NT-proBNP levels were highest in patients with severe and non-acute ischemia compared to those with severe and acute ischemia (182 (98-339) pmol/L vs 105 (28-324) pmol/L, p=0.012). There was a negative correlation between acuteness-score and log(NT-proBNP) in patients with severe ischemia (r=0.395, p=0.003), which remained significant in multilinear regression analysis (ß=-0.155, p=0.007). No correlation was observed between the acuteness-score and log(NT-proBNP) in patients with non-severe ischemia (p=0.529) or in the entire population (p=0.187). CONCLUSION: In STEMI patients with severe ischemia, neurohormonal activation is inversely associated with ECG patterns of acute myocardial ischemia.

Automatic QRS Selvester scoring system in patients with left bundle branch block.

AIMS: The Selvester QRS scoring system uses quantitative criteria from the standard 12-lead electrocardiogram (ECG) to estimate the myocardial scar size of patients, including those with left bundle branch block (LBBB). Automation of the scoring system could facilitate the clinical use of this technique which requires a set of multiple QRS patterns to be identified and measured. METHODS AND RESULTS: We developed a series of algorithms to automatically detect and measure the QRS parameters required for Selvester scoring. The 'QUantitative and Automatic REport of Selvester Score' was designed specifically for the analysis of ECGs from patients meeting new strict criteria for complete LBBB. The algorithms were designed using a training (n = 36) and a validation (n = 180) set of ECGs, consisting of signal-averaged 12-lead ECGs (1000 Hz sampling) recorded from 216 LBBB patients from the MADIT-CRT. We assessed the performance of the methods using expert manually adjudicated ECGs. The average of absolute differences between automatic and adjudicated Selvester scoring was 1.2 ± 1.5 points. The range of average differences for continuous measurements of wave locations and interval durations varied between 0 and 6 ms. Erroneous detection of Q, R, S, R', and S' waves (oversensed or missed) were 3, 1, 1, 16, and 6%, respectively. Seven percent of notches detected in the first 40 ms were misdetected. CONCLUSION: We propose an efficient computerized method for the automatic measurement of the Selvester score in patients with the strict LBBB.

Scientific STAFF and MALT meetings - past, present, and future.

The scientific STAFF and MALT meetings were created around the turn of the century for scientists engaged in enhancing the role of the 12-lead ECG for detection and quantification of involved myocardium in patients with acute coronary syndrome. These meetings were initially focused on computer processing of data from two single-center databases. The STAFF database was collected in the mid-nineties on patients with prolonged total coronary occlusion; high-resolution 12-lead ECGs were collected before, during, and after 5 minutes of occlusion. The MALT database was created in the early years of this century on consecutive patients with chest pain admitted to a large teaching hospital. Delayed enhancement magnetic resonance imaging and electrocardiograms were recorded in these acutely ill patients. The paper highlights the first 2 decades of the STAFF and MALT meetings and details the meeting format.

A 12-lead ECG-method for quantifying ischemia-induced QRS prolongation to estimate the severity of the acute myocardial event.

INTRODUCTION: Studies have shown terminal QRS distortion and resultant QRS prolongation during ischemia to be a sign of low cardiac protection and thus a faster rate of myocardial cell death. A recent study introduced a single lead method to quantify the severity of ischemia by estimating QRS prolongation. This paper introduces a 12-lead method that, in contrast to the previous method, does not require access to a prior ECG. METHODS: QRS duration was estimated in the lead that showed the maximal ST deviation according to a novel method. The degree of prolongation was determined by subtracting the measured QRS duration in the lead that showed the least ST deviation. RESULTS: The method is demonstrated in examples of acute occlusion in two of the major coronary arteries. CONCLUSION: This paper presents a 12-lead method to quantify the severity of ischemia, by measuring QRS prolongation, without requiring comparison with a previous ECG.

Validation of the vessel-specific leads (VSLs) for detection of acute ischemia on a dataset with non-ischemic ST-segment deviation.

BACKGROUND: Existing criteria recommended by ACC/ESC for identifying patients with ST elevation myocardial infarction (STEMI) from the 12-lead ECG perform with high specificity (SP) but low sensitivity (SE). In our previous studies, we found that the SE of acute ischemia detection can be markedly improved without any loss of SP by calculating, from the 12-lead ECG, ST deviation in 3 "optimal" vessel-specific leads (VSLs). To further validate the method, we evaluated the SP performance using a dataset with non-ischemic ST-segment changes. METHODS: 12-lead ECGs of 100 patients (75 males/25 females, age range 12-83years, average age 52years) were retrieved from a centralized ECG management system at Skåne University Hospital, Lund, Sweden. These ECGs were chosen to represent five subgroups with various causes of pathological ST deviation, other than acute coronary occlusion: a) ventricular preexcitation (n=12), b) acute pericarditis (n=26), c) early repolarization syndrome (ERS) (n=14), d) left ventricular hypertrophy (LVH) with "strain" (n=26), and e) left bundle branch block (LBBB) (n=22). ECGs with inadequate signal quality, heart rate exceeding 120bpm and/or atrial flutter were not selected for this study population. Both STEMI criteria and VSLs criteria with and without a new augmented LVH-specific derived lead were tested. SP, calculated for each subgroup and combined, was used as the performance measure for comparison. RESULTS: SP test results for the STEMI criteria vs. the VSLs method without the augmented LVH lead were 100% vs. 92%, 4% vs. 88%, 29% vs. 100%, 100% vs. 77%, and 64% vs. 68% for the five subgroups with preexcitation, pericarditis, ERS, LVH, and LBBB, respectively. For the whole group, SP was 57% for the STEMI criteria and 83% for the VSLs criteria; this improvement was statistically significant (p<0.001). With the augmented LVH lead, SP for the VSLs improved from 77% to 96% for the LVH subgroup and SP for the other subgroups remained unchanged. For the whole study group, SP improved from 83% to 88%. CONCLUSION: Based on these results, we conclude that the VSLs criteria are not only more sensitive in detecting acute ischemia but also more specific in recognizing patients with non-ischemic ST deviation than the existing STEMI criteria. This finding needs to be further corroborated on a larger patient population with AMI prevalence typical of the population presenting to the emergency room.

Pre-hospital electrocardiographic severity and acuteness scores predict left ventricular function in patients with ST elevation myocardial infarction.

OBJECTIVES: System delay (time from first medical contact to primary percutaneous coronary intervention) is associated with heart failure and mortality in patients with ST segment elevation myocardial infarction (STEMI). We evaluated the impact of system delay on left ventricular function (LVF) according to the combination of ischemia severity (Sclarovsky-Birnbaum grades) and acuteness (Anderson-Wilkins scores) in the pre-hospital electrocardiogram (ECG). METHODS: In a predefined secondary analysis of a prospective study, the severity and acuteness scores were performed on the pre-hospital ECG. Patients were assessed with respect to 4 classifications which were not mutually exclusive: severe ischemia (+SI) or non-severe ischemia (-SI) and acute ischemia (+AI) or non-acute ischemia (-AI). LVF was assessed by global longitudinal strain (GLS) within 48hours of admission. Adjusted linear regression investigated the association of system delay with GLS in each group. RESULTS: In total 262 patients were eligible for analysis of the ECG, which resulted in 42 (16%) with (+SI, -AI), 110 (42%) with (-SI, -AI), 90 (34%) with (-SI, +AI), and 20 (8%) patients with (+SI, +AI). Although system delay did not differ between groups, patients with severe and non-acute ischemia had the most impaired LVF. System delay correlated weakly with GLS in the entire population (r=0.133, p=0.031), and well with GLS in the (+SI, +AI) group (r=0.456, p=0.04), while there was no correlation in the other groups. By adjusted analysis, system delay predicted impaired GLS only in the (+SI, +AI) group (ß=0.578, p=0.002). CONCLUSION: Pre-hospital risk stratification by ECG identifies patients with acute and severe ischemia who are at increased risk for reduced ventricular function (assessed by GLS) after STEMI. Optimizing reperfusion delays in these patients can therefore be of particular benefit in improving clinical outcome after STEMI.

Evaluation of acute ischemia in pre-procedure ECG predicts myocardial salvage after primary PCI in STEMI patients with symptoms >12hours.

BACKGROUND: Primary percutaneous coronary intervention (pPCI) is recommended in patients with ST Elevation Myocardial Infarction (STEMI) and symptom duration <12hours. However, a considerable amount of myocardium might still be salvaged in STEMI patients with symptom durations >12hours (late-presenters). The Anderson-Wilkin's score (AW-score) estimates the acuteness of myocardial ischemia from the electrocardiogram (ECG) in STEMI patients. We hypothesized that the AW-score is superior to symptom duration in identifying substantial salvage potential in late-presenters. METHODS: The AW-score (range 1-4) was obtained from the pre-pPCI ECG in 55 late-presenters and symptoms 12-72 hours. Myocardial perfusion imaging was performed to assess area at risk before pPCI and after 30days to assess myocardial salvage index (MSI). We correlated both the AW-score and pain-to-balloon with MSI and determined the salvage potential (MSI) according to AW-score ≥3 (acute ischemia) and AW-score <3 (late ischemia). RESULTS: Late-presenters had median MSI 53% (inter quartile range (IQR) 27-89). The AW-score strongly correlated with MSI (ß=0.60, R(2)=0.36, p<0.0001), while pain-to-balloon time did not (ß=-0.21, R(2)=0.04, p=0.14). Patients with AW-score ≥3 (n=16) compared to those with AW-score <3 (n=27) had significant larger MSI (82.7% vs 41.5%, p=0.014). MSI>median was observed in 79% in patients with AW-score ≥3 vs 32% in patients with AW-score <3 (adjusted OR 6.74 [95% CI 1.35-33.69], p=0.02). CONCLUSION: AW-score was strongly associated with myocardial salvage while pain-to-balloon time was not. STEMI patients with symptom duration between 12 -72hours and AW-score ≥3 achieved substantial salvage after pPCI.

Ischemic QRS prolongation as a biomarker of severe myocardial ischemia.

BACKGROUND: Previous studies have shown that QRS prolongation is a sign of depressed collateral flow and increased rate of myocardial cell death during coronary occlusion. The aims of this study were to evaluate ischemic QRS prolongation as a biomarker of severe ischemia by establishing the relationship between prolongation and collateral flow experimentally in a dog model, and test if the same pattern of ischemic QRS prolongation occurs in man. METHODS: Degree of ischemic QRS prolongation was measured using a novel method in dogs (n=23) and patients (n=52) during coronary occlusion for 5min. Collateral arterial flow was assessed in the dogs. RESULTS: There was a significant correlation between QRS prolongation and collateral flow in dogs (r=0.61, p=0.008). Magnitude and temporal evolution of prolongation during ischemia were similar for dogs and humans (p=0.202 and p=0.911). CONCLUSION: Quantification of ischemic QRS prolongation could potentially be used as a biomarker for severe myocardial ischemia.

Left ventricular regional contraction abnormalities by echocardiographic speckle tracking in combined right bundle branch with left anterior fascicular block compared to left bundle branch block.

BACKGROUND: In contrast to LBBB patients less is known about patients with RBBB+LAFB regarding LV contractile abnormalities and the potential role of CRT. This study investigated whether patients with RBBB+LAFB morphology have echocardiographic mechanical strain abnormalities between the inferior and anterior LV walls, similar to abnormalities between septal and lateral walls in LBBB. METHODS AND RESULTS: Ten healthy volunteers with no-BBB, 28 LBBB and 28 RBBB+LAFB heart failure patients were included in this retrospective study. Two-dimensional regional-strains were obtained by speckle-tracking. Scar was assessed by CMR. Response on echo was defined as normal, classical, borderline or other pattern. The number of classical patterns in LBBB was significantly higher than in RBBB+LAFB and no-BBB groups (p<0.001 for both). Contrary, the RBBB+LAFB group showed a significantly higher number of borderline patterns compared to other groups (LBBB: p=0.042, no-block: p=0.012). In addition, RBBB+LAFB patients had more scar than LBBB patients (9.9% vs 3.4%, p=0.041), and the average amount of scar in each wall was also higher in RBBB+LAFB (<5% in LBBB and <16% in RBBB+LAFB). CONCLUSIONS: Patients with RBBB+LAFB on ECG and clinical HF demonstrate echocardiographic wall motion abnormalities between inferior and anterior LV walls, similar to abnormalities found between septal and lateral LV walls in patients with LBBB and HF. Fewer patients with RBBB+LAFB showed a classical pattern of opposing wall motion compared to LBBB. Factors that might alter strain patterns in RBBB+LAFB, including the detailed presence or absence of LV scar and coexisting block of the central fascicle, should be assessed in future studies.

Evaluation of Selvester QRS score for use in presence of conduction abnormalities in a broad population.

BACKGROUND: The Selvester QRS score is an electrocardiographic tool designed to quantify myocardial scar. It was updated in 2009 to expand its usefulness in patients with conduction abnormalities such as bundle-branch and fascicular blocks. There is need to further validate the updated score in a broader group of patients with cardiovascular disease and conduction abnormalities. We primarily hypothesized that the updated score could distinguish between presence and absence of scar by cardiac magnetic resonance imaging (CMR) with late gadolinium enhancement in 4 groups of patients with distinct conduction abnormalitites. METHODS: A total of 193 patients were retrospectively identified that had received an electrocardiogram (ECG) and a CMR scan at Duke University Medical Center between January 2011 and August 2013: 62 with left bundle-branch block, 51 with right bundle-branch block (RBBB), 43 with left anterior fascicular block (LAFB), and 37 with RBBB + LAFB. Scar sizes estimated by ECG and by CMR were compared using scatterplots, modified Bland-Altman plots, and receiver operating characteristics curves. RESULTS: Of 193 patients, 96 (50%) had no scar by CMR. The QRS score generally overestimated CMR scar. The area under the curve ranged between 0.62 and 0.65 for the different conduction types, and 95% confidence intervals included 0.5 for all conduction types. Performance was slightly improved in LAFB and RBBB + LAFB by excluding all points derived from leads V4-V6. CONCLUSIONS: The Selvester QRS score for use in conduction abnormalities needs to be improved, primarily its specificity, to enable effective clinical use in a population with a wide range of left ventricular ejection fraction and low pretest probability of myocardial scar.

Incidence of strict versus nonstrict left bundle branch block after transcatheter aortic valve replacement.

BACKGROUND: Up to one-third of patients diagnosed with left bundle branch block (LBBB) by conventional electrocardiographic (ECG) criteria are misdiagnosed. Strict LBBB shows decreased left ventricular pumping efficiency compared with nonstrict LBBB. However, no previous study has evaluated the frequency of strict LBBB after transcatheter aortic valve replacement (TAVR). The aim of this study was to determine the incidence of developing strict versus nonstrict LBBB after TAVR and test the hypothesis that preprocedure QRS duration does not predict strict LBBB but predicts development of nonstrict LBBB. METHODS: All patients receiving TAVR between 4/2011 and 2/2013 (n = 71) with no preexisting bundle branch block or permanent pacemaker were included. Twelve-lead ECGs were acquired preprocedure and both 1-day and 1-month postprocedure. All ECGs were classified as strict LBBB, nonstrict LBBB, or no LBBB. RESULTS: Sixty-eight patients had ECGs eligible for final analysis. On postprocedure day 1, 25 (37%) of 68 patients developed strict LBBB, and 2 patients (3%) developed nonstrict LBBB. At 1-month follow-up, the 2 patients diagnosed with nonstrict LBBB had resolved to normal, and 5 (20%) of 25 patients with strict LBBB had resolved to normal. Preprocedure QRS duration did not predict strict LBBB (P = .51). Because of the low incidence of nonstrict LBBB, QRS duration as a predictor of nonstrict LBBB could not be tested. CONCLUSIONS: Almost all patients who developed evidence of LBBB after TAVR met the new strict criteria, indicating probable procedural injury to the left bundle branch. Preprocedural QRS duration did not predict the development of strict LBBB.

The classical versus the Cabrera presentation system for resting electrocardiography: Impact on recognition and understanding of clinically important electrocardiographic changes.

The classical system for presentation of the 12-lead electrocardiogram (ECG) reflects the electrical activity of the heart as viewed in the transverse plane by 6 leads with a single anatomically ordered sequence, V1-V6; but in the frontal plane by 6 leads with dual sequences, I, II, and III, and aVR, aVL, and aVF. However, there is also a single anatomically ordered sequence of leads, called the Cabrera display that presents the six frontal plane leads in their anatomically ordered sequence of: aVL, I, -aVR, II, aVF, and III. Although it has been recognized that the Cabrera system has clinical diagnostic advantages compared to the classical display, it is currently only used in Sweden. The primary explanation of why the Cabrera system has not been adopted internationally has been that analog ECG recorders had technical limitations. Currently, however, the classical system is most often seen as a historical remnant that prevails because of conservatism within the cardiology community.

Comparison of model-based and expert-rule based electrocardiographic identification of the culprit artery in patients with acute coronary syndrome.

BACKGROUND AND PURPOSE: Culprit coronary artery assessment in the triage ECG of patients with suspected acute coronary syndrome (ACS) is relevant a priori knowledge preceding percutaneous coronary intervention (PCI). We compared a model-based automated method (Olson method) with an expert-rule based method for the culprit artery assessment. METHODS: In each of the 53 patients who were admitted with the working diagnosis of suspected ACS, scheduled for emergent angiography with a view on revascularization as initial treatment and subsequently found to have an angiographically documented completely occluded culprit artery, culprit artery location was assessed in the preceding ECG by both the model-based Olson method and the expert-rule based method that considered either visual or computer-measured J-point amplitudes. ECG culprit artery estimations were compared with the angiographic culprit lesion locations. Proportions of correct classifications were compared by a Z test at the 5% significance level. RESULTS: The Olson method performed slightly, but not significantly, better, when the expert-rule based method used visual assessment of J-point amplitudes (88.7% versus 81.1% correct; P=0.28). However, the Olson method performed significantly better when the expert-rule based method used computer-measured J-point amplitudes (88.7% versus 71.7% correct; P<0.05). CONCLUSION: The automated model-based Olson method performed at least at the level of expert cardiologists using a manual rule-based method.

Prevalence of manual Strauss LBBB criteria in patients diagnosed with the automated Glasgow LBBB criteria.

INTRODUCTION: About one-third of patients undergoing cardiac resynchronization therapy because of left bundle branch block (LBBB) and heart failure do not improve. Strauss et al. have developed strict criteria to more accurately define complete LBBB in this patient group. The aim of this study was to investigate the prevalence of the manual application of the Strauss criteria for LBBB (QRS ≥ 140 ms in men, ≥ 130 ms in women, along with mid-QRS notching/slurring) in consecutive patients who have been diagnosed with LBBB by the automated Glasgow criteria (QRS ≥ 120 ms). METHOD: In 158 consecutive patients (78 females) diagnosed with LBBB according to the automated Glasgow criteria, the manual Strauss criteria were applied. RESULTS & CONCLUSION: A majority of patients (87%) diagnosed with LBBB using the Glasgow criteria were positive for the Strauss criteria. In 70% (13/20) of the cases of disagreement the reason for disagreement was short QRS duration.

Specificity for each of the 46 criteria of the Selvester QRS score for electrocardiographic myocardial scar sizing in left bundle branch block.

BACKGROUND: The Selvester QRS score consists of a set of electrocardiographic criteria designed to identify, quantify and localize scar in the left ventricle using the morphology of the QRS complex. These criteria were updated in 2009 to expand their use to patients with underlying conduction abnormalities, but these versions have thus far only been validated in small and carefully selected populations. AIM: To determine the specificity for each of the criteria of the left bundle branch block (LBBB) modified Selvester QRS Score (LB-SS) in a population with strict LBBB and no myocardial scar as verified by cardiovascular magnetic resonance imaging with late gadolinium enhancement (CMR-LGE). METHODS: We identified ninety-nine patients with LBBB without scar on CMR-LGE, who underwent a clinically indicated CMR scan at three different centers. The ECG recording date was any time prior to or <30days after the CMR scan. The LB-SS was applied and specificity for detection of scar in each of the 46 separate criteria was determined. RESULTS: The specificity ranged between 41% and 100% for the 46 criteria of LB-SS and 27/46 (59%) met ≥95% specificity. The mean±SD specificity was 90%±14%. CONCLUSION: Several of the criteria in the LB-SS lack adequate specificity. Elimination or modification of these nonspecific QRS morphology criteria may improve the specificity of the overall LB-SS.

Validation of improved vessel-specific leads (VSLs) for detecting acute myocardial ischemia.

BACKGROUND: Existing criteria recommended by ACC/ESC for identifying patients with ST elevation myocardial infarction (STEMI) from the 12-lead ECG perform with high specificity (SP), but low sensitivity (SE). In our previous studies, we found that the SE of ischemia detection can be markedly improved without any loss of SP by calculating, from the 12-lead ECG, ST deviation in 3 "optimal" vessel-specific leads (VSLs). Our original VSLs, based on ΔST body-surface potential maps (BSPMs), have been modified by using the more appropriate J-point BSPMs at peak ischemia (without subtraction of pre-occlusion distributions). The aim of the present study was to compare the performance of these new VSLs with that achieved by the STEMI criteria used in current practice. METHODS: Two independent datasets of 12-lead ECGs were used: the STAFF III dataset acquired during ischemic episodes caused by balloon inflation in LAD (n=35), RCA (n=47), and LCx (n=17) coronary arteries, and the Glasgow dataset comprising admission 12-lead ECGs of 116 patients who were hospitalized for chest pain and underwent contrast-enhanced cardiac MRI that confirmed AMI in 58 patients (50%). RESULTS: We found that, in the STAFF III dataset, the detection of ischemic state by the STEMI criteria attained SE/SP of 60/97%, whereas SE/SP values of VSLs were 72/98%. In the Glasgow dataset, STEMI criteria yielded SE/SP of 43/98%, whereas the VSLs improved SE/SP to 60/98%. The most significant increase in diagnostic performance appeared in patients with LCx coronary artery occlusion: in STAFF III data (n=17) SE achieved by STEMI criteria was improved by the VSLs from 35% to 71%; in Glasgow data (n=12) SE of 31% achieved by STEMI criteria was improved by the VSLs to 69%. CONCLUSION: In our study population, existing ACC/ESC STEMI criteria complemented by the new VSLs yielded much improved sensitivity of ischemia detection without any detrimental effect on specificity. This finding needs to be corroborated on a larger chest-pain patient population with typical prevalence of acute ischemia presented to the emergency rooms.

Selvester scoring in patients with strict LBBB using the QUARESS software.

BACKGROUND: Estimation of the infarct size from body-surface ECGs in post-myocardial infarction patients has become possible using the Selvester scoring method. Automation of this scoring has been proposed in order to speed-up the measurement of the score and improving the inter-observer variability in computing a score that requires strong expertise in electrocardiography. In this work, we evaluated the quality of the QuAReSS software for delivering correct Selvester scoring in a set of standard 12-lead ECGs. METHOD: Standard 12-lead ECGs were recorded in 105 post-MI patients prescribed implantation of an implantable cardiodefibrillator (ICD). Amongst the 105 patients with standard clinical left bundle branch block (LBBB) patterns, 67 had a LBBB pattern meeting the strict criteria. The QuAReSS software was applied to these 67 tracings by two independent groups of cardiologists (from a clinical group and an ECG core laboratory) to measure the Selvester score semi-automatically. Using various level of agreement metrics, we compared the scores between groups and when automatically measured by the software. RESULTS: The average of the absolute difference in Selvester scores measured by the two independent groups was 1.4±1.5 score points, whereas the difference between automatic method and the two manual adjudications were 1.2±1.2 and 1.3±1.2 points. Eighty-two percent score agreement was observed between the two independent measurements when the difference of score was within two point ranges, while 90% and 84% score agreements were reached using the automatic method compared to the two manual adjudications. CONCLUSION: The study confirms that the QuAReSS software provides valid measurements of the Selvester score in patients with strict LBBB with minimal correction from cardiologists.

Investigation of potential mechanisms of sex differences in quinidine-induced torsade de pointes risk.

INTRODUCTION: The electrocardiographic index Tpeak-Tend has been proposed as a marker of dispersion of repolarization and may be a stronger predictor of torsade de pointes risk than QTc prolongation. METHODS AND RESULTS: We assessed whether quinidine-induced Tpeak-Tend prolongation is greater in women than men. The relationship between QTc prolongation and quinidine concentration was greater in women than men (38 ± 10 vs. 28 ± 9 ms/µg/ml, p=0.02), but there was no difference for Tpeak-Tend prolongation (39 ± 13 vs. 32 ± 13 ms/µg/ml, p=0.21). There was a delay (hysteresis) between peak concentration and both maximum QTc and Tpeak-Tend prolongation and a trend toward higher serum quinidine concentration in men than women. Analysis controlling for hysteresis showed no sex difference for QTc (55 ± 18 vs. 43 ± 19 ms/µg/ml, p=0.14), without changing the lack of sex difference with Tpeak-Tend (61 ± 22 vs. 55 ± 21 ms/µg/ml, p=0.49). CONCLUSIONS: Women do not have a greater quinidine-induced Tpeak-Tend prolongation than men. Sex differences in hysteresis and serum quinidine concentration in this study may have contributed to sex differences in quinidine-induced QTc prolongation.